THE residents of a supported-living home in south London are an active bunch. All six have severe learning disabilities and are cared for by ten full-time staff from Mencap, a charity. Nevertheless, once a month they discuss their ambitions with their key worker. About a year ago, one middle-aged client decided that she wanted to use public transport independently. Now she can catch the bus to a local café to have tea with a friend. Others are gardening at a local park or learning to cook. And their social workers occasionally throw them a party at a community hall, inviting other clients from nearby homes. The shindigs have even sparked a few romances.

Such capers are not what most people imagine when they think of social care. A more common view is of an elderly person in a old-folks’ home, or receiving occasional home visits from a helper. Headlines warn that Britain’s ageing population is putting a strain on the service. The number of people of retirement age has risen by 2m in the past ten years. A government green paper on social-care funding, announced in November, is likely to focus on the over-65s.

But that is by no means the whole picture. Although about twice as many over-65s receive social care as working-age adults—who include those with physical disabilities and mental illnesses, as well as people with learning disabilities—spending on the two groups is almost equal, at about £7bn ($9.7bn) each (see chart). And spending on working-age adults has been growing faster. In 2005 only six of the 151 local authorities in England spent more on care for working-age adults than they did on care for the elderly. Last year, 57 did. Much of this shift has to do with people with learning disabilities, who make up the fastest-growing part of councils’ social-care budgets.

Many reasons for the change are encouraging. One is that people with learning disabilities are living longer than they used to. More babies are surviving previously fatal conditions, such as premature birth, to reach adulthood with a learning disability. Medical advances help later in life, too. Today someone with Down’s syndrome can expect to live to 60. In the 1980s their life expectancy was 25.

They also lead better lives. Before the 1980s many were kept in long-stay hospitals, where living conditions were grim. Social workers at the home in south London say that some older clients struggle to kick habits from these times, such as sitting and watching washing machines so that no one can take their clothes. Now most people with learning disabilities live in community settings. Much more effort is put into finding them work or helping them become independent. But this is labour-intensive and thus costly. A ratio of three staff to one client is not uncommon.

Another reason is that most people with learning disabilities rely entirely on government funding, rather than their own savings, points out Andrew Cannon, head of Voyage Care, a provider. That gives cash-strapped local authorities less leeway to cut learning-disability services. Spending on this group increased by 2% in real terms between 2011 and 2014 (the most recent period for which years of comparable data are available), while dropping by 8% for adult social care overall.

Such trends are likely to continue. Last year a survey of the heads of local authorities’ social services found that the biggest factor in the increase in overall expected spending in 2018 would be people with learning disabilities, not the elderly.

One reason for this is a decision by the Department for Business regarding “sleep-ins”, explains Derek Lewis, the chairman of Mencap. These are night shifts that care workers spend at care homes in case of emergency. Partly because of their needs and partly because they tend to live in homes with relatively few residents, people with learning disabilities are more likely to need this level of care than the elderly. Previously, carers were reimbursed with a low flat rate for sleep-ins. The policy change means they must be paid an hourly wage for their time. That cost may be borne by local authorities or providers, depending on how care contracts are drawn up.

Many local authorities have agreed to absorb this cost, but not all. And the tax office has decided that social-care employers are liable for up to six years of back pay. That will cost the providers of care for those with learning disabilities an estimated £400m. Many are furious. They say that the government should stump up the cash, otherwise small suppliers, which make up most of the market, could go bust. A legal challenge to this decision will be heard in March at the Court of Appeal.

Whatever the outcome on back pay, the new policy on sleep-ins will drive up spending on social care. The cost to the taxpayer will not be known for several years, as local authorities decide how to pay for overnight stays. But on present trends, looking after working-age adults may soon cost more than caring for the elderly.